The light charged particle emission following the fusion of ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$ with ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$ at 100–150 MeV bombarding energies in 10 MeV steps has been studied. Energy spectra and angular distributions of p, d, t, and alpha particles as well as light-particle–light-particle coincidences have been measured. The light charged particle data and the published evaporation residue distributions are compared with statistical model calculations. The comparison shows that the statistical model describes well the experimental observables if account is taken of changes in the level density and barrier apparently due to the onset of deformations at high spins. The spectra of α particles emitted from narrow windows of angular momentum with 28ħ≤$J_{\mathrm{ave}\mathrm{\le }34\mathrm{ħ}}$ have been obtained by means of a subtraction procedure and analyzed to extract emission barriers and level density enhancement factors. The deduced barrier lowering with respect to the spherical barrier is somewhat greater than that predicted by assuming rotating liquid drop model (RLDM) shapes. The level density enhancement factor is comparable with that determined in the past for statistically deformed nuclei.

We continue our study of dilepton radiation from high-temperature nuclear matter by computing the rates for the annihilations $K^{+}$$K^{\mathrm{-}}$→$e^{+}$$e^{\mathrm{-}}$ and NN¯→$e^{+}$$e^{\mathrm{-}}$. In general this radiation would yield information on the abundances of kaons and antinucleons in hot and dense nuclear matter. More specifically, the former may yield information on the approach to kaon condensation, and the latter may yield information on the nucleon-antinucleon dispersion relations as predicted by relativistic field theories of nuclear matter. However, these yields are mostly overshadowed by the processes np→${\mathrm{npe}}^{+}$$e^{\mathrm{-}}$ and ${\pi }^{+}$${\pi }^{\mathrm{-}}$→$e^{+}$$e^{\mathrm{-}}$, so that dilepton production remains essentially a probe of pion dynamics in the nuclear medium.

Coupled-reaction channels calculations for ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${(}^7$Li${,}^6$Li${)}^{13}$C ${(1/2\mathrm{}}^{+}$, 3.09 MeV) which include the reorientation of ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$, excitation of the ${(1/2\mathrm{}}^{\mathrm{-}}$ 0.48 MeV state of ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$, the transition from this state to the ground state of ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$, and transitions between the ground and first excited state of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$, are almost identical to finite-range distorted-wave Born approximation calculations, and are highly oscillatory, whereas the data are structureless. These calculations show that multistep processes between ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$ and ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ are not responsible for producing the unstructured l=1 transfer measured in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${(}^7$Li${,}^6$Li${)}^{13}$C ${(1/2\mathrm{}}^{+}$, 3.09 MeV). Data are reported for elastic and inelastic scattering of ${}_{}{}^7{}_{}{}^{}$Li${+}^{16}$O and the single nucleon transfers ${(}^7$Li${,}^6$Li${/}^6$He). Once again, the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$${(}^7$Li${,}^6$Li${)}^{17}$O ${(1/2\mathrm{}}^{+}$, 0.87 MeV) angular distribution data are structureless, while finite-range distorted-wave Born approximation calculations are highly structured.

Assuming that two neutrons in ${}_{}{}^{11}{}_{}{}^{}\mathrm{Li}$ form a ‘‘halo’’, we derive phenomenologically the narrow component of the width of the momentum distribution of ${}_{}{}^9{}_{}{}^{}\mathrm{Li}$ from the fragmentation of ${}_{}{}^{11}{}_{}{}^{}\mathrm{Li}$ using a diffractive excitation model. The binding energy of the two neutrons in the halo is estimated and the momentum widths of other heavy fragments are also given.

High spin states of ${}_{}{}^{189}{}_{}{}^{}\mathrm{Tl}$ have been populated through the fusion-evaporation reactions ${}_{}{}^{169}{}_{}{}^{}[_{}^{24}{}_{}{}^{}$Mg(125 MeV),4n], ${}_{}{}^{165}{}_{}{}^{}[_{}^{28}{}_{}{}^{}$Si(140 MeV),4n], and ${}_{}{}^{175}{}_{}{}^{}[_{}^{20}{}_{}{}^{}$Ne(128 MeV),6n] and its subsequent decay studied by in-beam γ-ray spectroscopy techniques. Among the firmly established features there are two band structures resulting from the coupling of the h(9/2 and i(13/2 proton intruder states to the oblate ground-state band of the Hg core. However, above a certain excitation energy both bands show structural changes possibly related to the prolate shaped excited band in ${}_{}{}^{188}{}_{}{}^{}\mathrm{Hg}$. At least for the π̃i(13/2 case, coexistence of both shapes is observed.

Recent experimental data for light particle and complex fragment emission are compared to the results of a microcanonical statistical fragmentation model. The entropy produced in the reactions is extracted by varying the breakup temperature and density. The best fit to the data is nearly independent of the temperature and density. The extracted entropy is somewhat higher for light particles than for complex fragments.

The pionic fusion reaction ${}_{}{}^{12}{}_{}{}^{}\mathrm{He}$,${\pi }^{+}$${)}^{15}$N has been measured at 170.2 and 236.3 MeV bombarding energy using recoil detection. At $T_{{}_{}{}^3{}_{}{}^{}\mathrm{He}}$=170.2 MeV the angle-integrated cross section for the population of both the ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}_{\mathrm{g}.\mathrm{s}.\mathrm{}}^{}{}_{}{}^{}$ and a broad group of unresolved ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$ excited states between $E_x$=6 and 10 MeV is less than 0.03 nb. At $T_{{}_{}{}^3{}_{}{}^{}\mathrm{He}}$=236.3 MeV the total cross section summed over both groups is (0.8±0.2) nb.

The importance and usefulness of crossing is emphasized for both kaon scattering and kaon production reactions. It is argued, and numerically demonstrated for a chiral Lagrangian, that crossing provides powerful, comprehensive constraints which are often neglected in the evaluation of dynamical models. Cross section calculations are presented for two distinct sets of crossing related reactions: (1) $K^{\mathrm{-}}$p→$K^{\mathrm{-}}$p, $K^{+}$p→$K^{+}$p and p¯p→$K^{\mathrm{-}}$$K^{+}$; (2) $K^{\mathrm{-}}$p→γΛ and γp→$K^{+}$Λ. The crossing relations require that the same hadronic Lagrangian, including coupling constants, govern all of these reactions, and results show that different reactions exhibit different sensitivity to coupling constant uncertainty. Because crossed reactions always entail different kinematic regions of the S matrix, it is expected that such sensitivity is not just representative of the current model but rather a general feature that should be exploited when investigating all relativistic theories.

Data on the level spectra of Λ hypernuclei, obtained from (${\pi }^{+}$,$K^{+}$) and ($K^{\mathrm{-}}$,${\pi }^{\mathrm{-}}$) reaction studies, are analyzed to obtain a density-dependent and nonlocal Λ-nucleus potential. We relate our results to previous work which bears on the origin of the density dependence and nonlocality of the Λ-nucleus potential. We argue that the distinguishable Λ particle provides one of the best examples of single-particle shell structure in nuclear physics.

We report the first observation of the isospin splitting of the giant dipole resonance built on the isobaric analog state. Three giant resonances were observed in (${\pi }^{+}$,${\pi }^{\mathrm{-}}$) double charge exchange (at $T_{\pi }$=292 MeV) on ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ at excitation energies of 25.7, 30.0, and 33.5 MeV (Q=-31.4, -35.7, and -39.2 MeV). Angular distributions were measured for the resonances and each observed to have a dipole shape. The cross-section ratios of the resonances are in close agreement with simple isospin geometry arguments for an isovector excitation built on the isobaric analog state. The summed cross section agrees well with simple sequential-model calculations in which the intermediate states arise from single charge exchange to the isobaric analog state and to the giant dipole resonance. We identify the three resonances as the isospin members of the charge-exchange dipole built on the isobaric analog state.

The threefold differential cross sections for the reaction ${\pi }^{+}$d→${\Delta }^{++}$n→${\pi }^{+}$pn were measured in a kinematically complete experiment as a function of beam momentum and the Δ(1232) production angle. The cross sections were measured at seven beam momenta between 312 and 600 MeV/c for ${\theta }_{\Delta }$=55° and 91° in the center-of-mass system. Angular distributions from 30° to 119° (c.m.) were taken at beam momenta of 350 and 425 MeV/c. These data are compared with predictions from a unitary, relativistic, three-body theory based on the Faddeev equations and with a multiple scattering theory. The theories reproduce the general trend of the data except at the highest energies.

Differential cross sections for the reaction ${}_{}{}^2{}_{}{}^{}(\mathit{p}$,2p)n at $T_p$=507 and 508 MeV are presented. The kinematics selected included two quasi-free angle pairs: 41.5°-41.4° and 30.1°-53.75°; in addition, data away from the quasi-free condition were obtained in four symmetric angle pairs: 38.1°-38.0°, 44.1°-44.0°, 47.1°-47.0°, and 50.0°-50.0°, and five asymmetric angles pairs: 30.1°-37.0°, 30.1°-44.0°, 30.1°-61.0°, 30.1°-68.0°, and 41.5°-50.0°. The data range over an energy window 100 MeV wide on one of the proton energies, the second energy being defined by the kinematic condition of a single neutron recoiling. The data are compared with the impulse approximation prediction and with the results of a nonrelativistic calculation of the six lowest-order Feynman diagrams describing the reaction. A previously known missing strength for the reaction in the small neutron recoil region is confirmed with much smaller experimental uncertainty; the missing strength persists up to 150 MeV/c neutron recoil. The onset of a systematic cross section excess relative to the impulse approximation near neutron recoil momentum 200 MeV/c is explored in detail.

The nonrelativistic multiple scattering formalism of Watson and Kerman, McManus, and Thaler is applied to the deuteron-nucleus elastic scattering system. An optical potential is constructed to second order in the nucleon-nucleon effective interaction t matrix and is organized in such a way that the usual Watanabe folding potential appears as the leading term. The Watanabe folding potential is constructed by integrating nucleon-nucleus optical potentials evaluated at half the deuteron incident kinetic energy over the deuteron s-state wave function. Corrections to the folding potential are identified which arise from deuteron-nucleon double scattering effects, the deuteron d state, virtual deuteron breakup, additional nuclear medium effects, additional target nucleon correlation effects, and relativistic processes. Many of these corrections do not appear in folding model approaches based on effective, rather than microscopic, deuteron-nucleus Hamiltonians. These additional multiple scattering corrections are second order in the nucleon-nucleon t matrix as is the case for the virtual deuteron breakup process which is often included in numerical calculations. Estimates of several of these additional multiple scattering corrections are provided for 700 MeV deuteron-nucleus elastic scattering. Most are found to be quite small. However, the additional effects of the nuclear medium beyond that already included in the input nucleon-nucleus optical potentials are significant and are comparable in magnitude to the effects of virtual deuteron breakup. It is intended that this multiple scattering approach be applied to deuteron-nucleus elastic scattering at energies of several hundred MeV. Calculations based on this method are presented and compared to recent data for 700 MeV d${+}^{40}$Ca and ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ elastic scattering.

Proton-induced spallation reactions are studied using the cascade-evaporation model. Glauber’s multiple scattering theory is used for treating the first stage of the reaction while the second stage is treated by assuming that the mass loss by the residual nucleus is a Poisson random process. An analytical expression is obtained for the cross section of producing a fragment of mass $A_F$ in a spallation process, which is able to reproduce the experimental excitation functions without any free parameter.

Angle-integrated cross-section measurements for the reaction ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$(${\pi }^{+}$,${\pi }^0$${)}^{13}$ N(g.s.), made with activation techniques, are presented for the energy range 50–350 MeV. These results are compared to earlier data for the same reaction and to differential cross-section measurements on other light nuclei. A deep minimum is observed near 70 MeV in the excitation function; it reflects the s- and p-wave interference minimum seen in the free-nucleon single-charge-exchange cross section. The data are compared to several optical-model calculations.

The photoproton knockout reaction on ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ leaving ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$ in low-lying bound states has been observed over the photon energy range from 196 to 361 MeV. The angular distribution for the reaction populating the ground state of ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$ develops sharp structure as the photon energy is increased but that for population of the excited states is smooth. The results are not explained by existing theoretical models.

The elastic scattering of 800 MeV polarized protons, with longitudinal, normal, and sideways orientations, from deuterons polarized normal to the scattering plane has been measured. The four-momentum transfer interval measured in this experiment is from 0.03 to 0.17 (GeV/c${)}^2$. Spin-correlation and spin-transfer observables have been extracted from the data. This experiment is one of a series designed to determine a number of observables in excess of the minimum number required to reconstruct the 12 subamplitudes of the proton-deuteron elastic scattering amplitude directly from spin observables. A comparison of the data with theoretical calculations employing three different phase-shift solutions for NN amplitudes reveals that sizable ambiguities exist in the values of NN amplitudes at small momentum transfers.

The inclusive production of $K_s^0$, Λ, Λ¯, and $K_s^0$Λ in the p¯Ta reaction at 4 GeV/c was measured and compared with that in the p¯p reaction. The total inelastic and topological cross sections were also measured. The number of Λ’s produced in the p¯Ta reaction was 11.3 times larger than that expected from the geometrical cross section, which is defined as $A^{2/3}$ times the cross section for the p¯p reaction. The yield ratio Λ¯/Λ was found to be 2×${10}^{\mathrm{-}2}$. These values cannot be accounted for by a straightforward extension of the p¯N reaction. Besides, a correlation of 2 vees like $K_s^0$-Λ could not prove their simultaneous production. Nuclear temperatures of 135 and 97 MeV were obtained from the kinetic energy spectra of $K_s^0$ and Λ, respectively. The kinematical characteristics of the $K_s^0$ and Λ produced were analyzed in terms of the fireball model.

An analytic distorted-wave Born approximation approach to Coulomb distortion effects up to (Zα${)}^2$ terms in inclusive and exclusive quasifree scattering is proposed. Applications to ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ are discussed and a new longitudinal-transverse separation procedure is investigated. The positron cross section is studied in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$.

The magnetic moment, quadrupole moment, and isotope shift of the radioactive isotope ${}_{}{}^{170}{}_{}{}^{}\mathrm{Tm}$ have been measured by the atomic-beam resonance-fluorescence technique. Hyperfine structures of the 563-, 568-, 590-, and 597-nm transitions were observed with a resolution of 12 MHz. The magnetic moment is found to be ${\mu }^{\mathrm{}\left(170\right)\mathrm{}}$=+0.2458(17) ${\mu }_N$; the spectroscopic quadrupole moment, $Q_s^{\mathrm{}\left(170\right)\mathrm{}}$=0.72(5) b. The isotope shifts δ${\nu }^{169}$,170 for the above lines are -469(2), -471(6), +462(6), and -461(8) MHz, respectively.